(CBS News) FREMONT, Calif. - Mitt Romney made a surprise campaign stop on Thursday at the solar-panel firm Solyndra LLC, where he sought to use the bankrupt company as an example of how he says President Obama is hostile to job creation.

The presumptive nominee's visit to the failed solar-energy plant culminates a week-long push to depict the president as clueless when it comes to handling the economy. By focusing on Solyndra, a company that was selected for a $535 million Energy Department loan-guarantee but later filed for bankruptcy and laid off its entire staff, Romney argued that Obama doesn't understand the free market and has wasted taxpayer dollars.

"President Obama was here to tout this building and this business as a symbol of the success of his stimulus," Romney said. "Well, you can see that it's a symbol of something very different today."

Romney noted a recent Treasury Department inspector general's report that the loan guarantee was "rushed," something he said was done to reward Obama administration supporters running the company.

"It's also a symbol of how the president thinks about free enterprise. Free enterprise to the president means taking money from the taxpayers and giving it freely to his friends," he said.

Republicans have not found evidence to back up claims by some lawmakers that the loan was approved for political reasons. But Solyndra has been a popular punching bag for conservatives, who have used its collapse as a focal point for attacks against the White House's green-energy policies.

Two wealthy outside right-wing interest groups reportedly have spent more than $9 million attacking Obama on the issue. House Republicans also have probed deeply into the company's demise and what the GOP contends has been the Obama administration's obstruction of their efforts.

But polls last year showed that voters did not yet share that outrage. Former California GOP Gov. Arnold Schwarzenegger has said he considers the debate narrow-minded in a world moving faster toward renewable energy.

Romney's visit to Solyndra was conducted under strict secrecy. It was not on his daily advance schedule and reporters were told not to report his visit there until right before he arrived. The event was held across the street from the company, with Romney positioned on a podium just off the road.

"I think there are people who don't want to see this event occur, don't want to have questions asked about this particular investment, don't want to have people delve into the idea that the president took a half a billion dollars of taxpayer money and devoted it to an enterprise that was owned in large measure by his campaign contributors," Romney said when asked about the secrecy.

Nevertheless, the Obama campaign was ready for the Solyndra salvo. It issued a news release before Romney's visit accusing their rival of ignoring "his own record of using taxpayer money to pick winners and losers--some who were donors to his campaign" when he was Massachusetts' governor.

"The reality is that Solyndra received funding through a Department of Energy program created under the Bush administration - a program that has supported tens of thousands of jobs across the country and is moving forward with investments in innovative projects like the first nuclear plant built in the U.S. in decades and the world's largest wind farm," spokeswoman Lis Smith said.

"In fact, both Republican and Democratic administrations advanced Solyndra's application, and the company was widely praised as successful and innovative both before and after receiving the Department of Energy loan guarantee."

Romney, when asked about the Bush administration's ties to the program, said the decision to single out Solyndra was an Obama adminstration move. "This was a decision to say that the money would go in to Solyndra to campaign contributors, very large campaign contributors, of President Obama," he said. "That had nothing to do with predecessors."

And with Romney making such an issue of Solyndra, he has risked having his own business background opened to even further scrutiny. Democratic National Committee spokesman Brad Woodhouse emailed reporters a Boston Herald article from December that said when Romney was governor, the state handed out $4.5 million in loans to two firms run by his campaign donors that have since defaulted. Woodhouse's email was headlined, "Two Can Play at This Game."

The Obama campaign continues to go after Romney for his record as the CEO of Bain Capital. The president and his team have spent the past several weeks trying to portray Romney as more concerned with profit than job creation, by focusing on companies that were taken over by the venture-capital firm that ended up in bankruptcy and laying off their employees.

Speaking at a fundraiser on Wednesday night at the Carolands mansion in Hillsborough, Calif., Romney sought to turn the tables on Mr. Obama, suggesting that the government's investment in Solyndra was an example of the president trying to be a venture capitalist, but with taxpayer dollars.

"Have you seen Solyndra's corporate headquarters?" Romney asked the crowd of over 300 donors, referencing the bankrupt company's multi-million dollar office facility and plant built with the help of government loans. "That's what happens when government puts in hundreds of millions of dollars into an enterprise."

Romney suggested that by investing in Solyndra, the Obama administration had likely stifled competition in the solar panel industry because other investors would be less likely to fund their own companies when faced with the government as a competitor.

"Who wants to put money in a solar company when a government puts a half a billion into one of its choice?" Romney asked. "So instead of encouraging solar energy, he discouraged it. They don't understand how the free economy works."